Larkhall Natural Health was found guilty of three charges under the Trades Description Act relating to the packaging of its tablets called Tandem IQ. It is the third manufacturer of vitamin pills to be prosecuted this year.
In the latest case brought by Shropshire County Council's trading standards department, the stipendiary magistrate, Harry Hatchard, said he was satisfied there was reliable evidence that only children with a dietary deficiency were likely to benefit from vitamin and mineral supplements.
He was also satisfied that a significant number of potential customers could be misled into thinking that the tablets were capable of a general and widespread effect in increasing the IQ of children.
After the hearing David Walker, of Shropshire trading standards department, said: 'If this means that generalised claims that taking these supplements will increase your child's IQ are no longer used, then we will have achieved our purpose.'
A spokesman for the London- based company said it was considering an appeal.
The controversy over vitamins and IQ began four years ago. It had seemed like the answer to every parent's prayer. A daily dose would improve the intelligence of their children. Scientists said so.
It was such a simple remedy and relatively cheap. The manufacturers of health food supplements were even more enchanted by the possibilities. Sales rocketed.
Claims of the power of vitamins to improve health and intelligence have been made since the 1940s and many trials in Third World countries have attested to the benefits of treating vitamin deficiency.
The most recent arguments have involved claims and counter claims from scientists, statements from the Department of Health and the Medical Research Council and programmes on television.
In 1988, Dr David Benton, a research psychologist at the University of Wales at Swansea, published results of a study of two groups of 12 year-olds given either vitamin and mineral supplements or placebo pills. The children on the supplements did better in subsequent non-verbal reasoning tests. His work was reported in the television programme QED and the formula he used for his research was subsequently marketed at Tandem IQ. Dr Benton concluded that children who were nutritionally deficient might benefit.
His work was supported by other studies, particularly from America. Last year Professor Stephen Schoentaler, of California State University, made similar claims. His results were launched in Britain at the same time as a vitamin and mineral supplement designed for children. This work was also reported on QED.
At the same time other studies could find no benefit in children taking the supplements. These scientists did not argue that their colleagues were wrong, rather that there is insufficient evidence to make claims for improving IQ.
In 1990, David Maclean, who was minister responsible for food safety, advised parents that some claims made for the supplements were false and that taking pills was unnecessary for the majority.
But the idea that vitamins boost intelligence was far more memorable and attractive than the idea that they do not. In 1990, according to a recent edition of the Consumers' Association's Which? Way to Health, Britons spent pounds 52m on vitamin and mineral supplements.
The publication, having studied the available research, also concluded that there was no evidence that they relieved stress, increased energy or boosted intelligence.
The orthodox view is that the type of diet eaten by British children is varied enough to be entirely adequate, even if it is in some cases too heavy on burgers and crisps.
Dr Michael Nelson, lecturer in nutrition at King's College, London, who gave evidence in the Tandem IQ case said that if there was an argument for these supplements for children then it would be among the families the least able to afford them.